As Mitt Romney continues to fend off attacks from the Obama campaign, he’s facing a form of “friendly fire” that’s becoming less and less friendly.

Prominent Republicans have been voicing frustration with Mr. Romney for weeks now, over everything from his unwillingness to release more of his tax returns to what they see as his campaign’s flat-footedness in responding to Democratic attacks.

Over on ABC’s “This Week,” conservative columnist George Will chimed in by observing that Romney was “losing at this point in a big way.” Mr. Will added: “I do not know why, given that Mitt Romney knew the day that McCain lost in 2008 that he was going to run for president again that he didn't get all of this out and tidy up some of his offshore accounts and all the rest.”

Former Bush strategist Matthew Dowd then twisted the knife further by actually speculating that there is something damaging in the tax returns: “There's obviously something there, because if there was nothing there, he would say, ‘Have at it,’” Mr. Dowd commented. “So there's obviously something there that compromises what he said in the past about something…. [I]f he had 20 years of great, clean, everything's fine, it'd all be out there.”

Yikes.

Some of these folks were conspicuously not in Romney’s corner during the GOP primary campaign. Mr. Will’s wife worked briefly on Texas Gov. Rick Perry’s ill-fated presidential bid, and Will was a fairly harsh critic of Romney throughout the primary season. Mr. Kristol was one of those calling for a new candidate to jump into the race even after it was pretty clear that the field was set.

But that doesn’t mean the comments won’t hurt.

Our question is whether there’s anything Romney can do at this point to appease these critics (aside from releasing the tax returns –which at this point, we suspect, won't even do it). Maybe include them all in some campaign strategy sessions? Launch a personal charm offensive? Write some checks? (Just kidding.)

Actually, his best solution might lie with his vice presidential pick. By tapping a running mate who excites those Republicans least excited about Romney himself, Romney might finally silence some of the naysayers who’ve been nipping at him.

Of course, those are not the candidates most often cited as the true frontrunners (those would be Ohio Sen. Rob Portman and former Minnesota Gov. Tim Pawlenty). Which means Romney may be about to disappoint his critics on the right again. Watch out for the knives.